Automatic sprinkler systems are some of the most widely used devices for fire protection. These systems have sprinklers that are activated once the ambient temperature in an environment, such as a room or building exceeds a predetermined value. Once activated, the sprinklers distribute fire-extinguishing fluid, preferably water, in the room or building. A sprinkler system is considered effective if it extinguishes or prevents growth of a fire. The effectiveness of a sprinkler is dependent upon the sprinkler consistently delivering an expected flow rate of fluid from its outlet for a given pressure at its inlet. The discharge coefficient or K-factor of a sprinkler allows for an approximation of flow rate to be expected from an outlet of a sprinkler based on the square root of the pressure of fluid fed into the inlet of the sprinkler. As used herein and the sprinkler industry, the K-factor is a measurement used to indicate the flow capacity of a sprinkler. More specifically, the K-factor is a constant representing a sprinkler's discharge coefficient, that is quantified by the flow of fluid in gallons per minute (GPM) through the sprinkler passageway divided by the square root of the pressure of the flow of fluid fed to the sprinkler in pounds per square inch gauge (PSIG.). The K-factor is expressed as GPM/(PSI)1/2. Industry accepted standards, such as for example, the National Fire Protection Association (NFPA) standard entitled, “NFPA 13: Standards for the Installation of Sprinkler Systems” (2010 ed.) (“NFPA 13”) provides for a rated or nominal K-factor or rated discharge coefficient of a sprinkler as a mean value over a K-factor range. As used herein, “nominal” describes a numerical value, designated under an accepted standard, about which a measured parameter may vary as defined by an accepted tolerance. For example, for a K-factor greater than 14, NFPA 13 provides the following nominal K-factors (with the K-factor range shown in parenthesis): (i) 16.8 (16.0-17.6) GPM/(PSI)1/2; (ii) 19.6 (18.6-20.6) GPM/(PSI)1/2; (iii) 22.4 (21.3-23.5) GPM/(PSI)1/2; (iv) 25.2 (23.9-26.5) GPM/(PSI)1/2; (v) 28.0 (26.6-29.4) GPM/(PSI)1/2; and 33.6 (31.9-35.3) GPM/(PSI)1/2.
The fluid supply for a sprinkler system may include, for example, an underground water main that enters the building to supply a vertical riser. At the top of a vertical riser, an array of pipes extends throughout the fire compartment in the building. In the piping distribution network atop the riser includes branch lines that carry the pressurized supply fluid to the sprinklers. A sprinkler may extend up from a branch line, placing the sprinkler relatively close to the ceiling, or a sprinkler can be pendent below the branch line. For use with concealed piping, a flush-mounted pendent sprinkler may extend only slightly below the ceiling.
Fluid for fighting a fire can be provided to the sprinklers in various configurations. In a wet-pipe system, for buildings having heated spaces for piping branch lines, all the system pipes contain water for immediate release through any sprinkler that is activated. In a dry-pipe system, branch lines and other distribution pipes may contain a dry gas (air or nitrogen) under pressure. Dry pipe systems may be used to protect unheated open areas, cold rooms, buildings in freezing climates, cold-storage rooms passageways, storage or other occupancies exposed to freezing temperatures, such as unheated. The gas pressure in the distribution pipes may be used to hold closed a dry pipe valve at the riser to control the flow of fire fighting liquid to the distribution piping. When heat from a fire activates a sprinkler, the gas escapes and the dry-pipe valve trips, water enters branch lines, and fire fighting begins as the sprinkler distributes the fluid.
Dry sprinklers may be used where the sprinklers may be exposed to freezing temperatures. NFPA 13 defines a dry sprinkler as a “sprinkler secured in an extension nipple that has a seal at the inlet end to prevent water from entering the nipple until the sprinkler operates.” Accordingly, a dry sprinkler may include an inlet containing a seal or closure assembly, some length of tubing connected to the inlet, and a fluid deflecting structure, such as for example, a sprinkler body or frame and deflector located at the other end of the tubing. There may also be a mechanism that connects a thermally responsive component to the closure assembly. The inlet is preferably secured to a branch line by one of a threaded-type coupling or a clamp or grooved-type coupling. Depending on the particular installation, the branch line may be filled with fluid (wet pipe system) or be filled with a gas (dry pipe system). In either installation, the medium within the branch line is generally excluded from the passageway of the extension nipple or tubing of the dry sprinkler via the closure assembly in an unactuated state of the dry sprinkler. Upon activation of the thermally responsive component, the dry sprinkler is actuated and the closure assembly is displaced to permit the flow of fluid through the sprinkler.
In known dry sprinklers, an arrangement of internal components is provided to position the closure assembly in both the actuated and unactuated state of the sprinkler. In the actuated state, the internal components in combination with the thermally responsive component, positions the closure assembly at a sealing surface to provide a fluid seal at the inlet end of the unactuated dry sprinkler. The internal components, upon activation of the thermally responsive component, positions the closure assembly within the passageway to permit flow through the dry sprinkler in accordance with the rated discharge coefficient or nominal K-factor of the sprinkler. Accordingly, the internal components and closure assembly of the sprinkler and their geometry within the inlet and passageway of the sprinkler can impact the performance and effectiveness of the sprinkler. For known embodiments of dry sprinklers, as seen for example, in U.S. Pat. Nos. 7,559,376 and 7,516,800, the seal assembly-to-sealing surface contact at the inlet of the sprinkler may provide little internal volume for the seal assembly or its support member(s) once the sprinkler is actuated. To permit the desired flow through the sprinkler, some known sprinklers employ rotating sealing assemblies to displace the seal out of the water flow path. However, with increasing K-factor, a greater force is generally required to rotate or alter the position of the sealing assembly. The presence of the seal assembly in the internal volume of the inlet after actuation may present an unsuitable resistance to water flow thereby inhibiting the ability of the dry sprinkler to achieve particular rated K-factors with certain nominal sized threaded inlets. This resistance can prevent high K-factors, e.g., greater than 14 and in particularly, nominal 16.8 GPM/PSI1/2 or greater, with the certain nominal sized threaded inlets.
U.S. Published Patent Application No. 2007/0187116 to Jackson et al. describes and shows one known dry sprinkler. Jackson et al. describe the dry pipe sprinkler as including a sprinkler body having a thermally responsive trigger mounted thereto. A housing, including an inlet end and an outlet end, is provided with the outlet end being connected to the sprinkler body. A seal member is disposed at the inlet end of the housing, and a load mechanism extends between the thermally responsive element and the seal member. The load mechanism may include a support portion, a passage tube portion, and an outlet orifice portion slidably received within the housing and movable within the housing upon activation of the thermally responsive trigger to allow the seal member to be dislodged from the inlet end of the housing to allow suppressant fluid to flow therethrough. FIGS. 15 and 16 of Jackson et al. show the inlet body 22 can be provided with external threads 64 for threadedly engaging the system piping. Alternatively, as shown in FIG. 17, the inlet body 22′ can be configured to provide a grooved inlet connection with the sprinkler system piping 8 or, alternatively, can be provided with other coupling configurations. Jackson et al. therefore describes and shows removing and replacing one inlet body with another inlet body in order to provide different alternative connections. Jackson et al., accordingly, fails to describe or show concurrently providing alternative couplings. More specifically, Jackson et al. does not show a single dry sprinkler structure having two or more coupling configurations to provide multiple modes for connection to a system piping.
There exists a need for a single dry sprinkler that can achieve various nominal K-factors for various nominal inlet sizes; and in addition have multiple alternative coupling arrangements that can, in combination with an arrangement of internal sprinkler components, provide the desired flow characteristics for a given fluid inlet pressure so as to satisfy the designed nominal K-factor or rated discharge coefficient of the sprinkler. It is also desirable to have a dry sprinkler with an internal assembly that locates its seal assembly within the sprinkler inlet upon actuation so as to permit a desire flow for the nominal K-factor of the sprinkler in combination with a desired inlet and casing tube extension size and configuration. Moreover, there is a need for the alternative coupling arrangements to be able to connect to standard pipe fittings, i.e., T-fittings, pipe nipples, pipe reducers, etc, that may be encountered in either a wet or dry sprinkler system. Accordingly, where it is desirable to have a single configuration of a dry sprinkler for either wet or dry system installation, it may be desirable to have an internal structural configuration for only one of a wet or dry system installation or alternatively both a wet and a dry system installation. In addition, it is desirable for the dry sprinkler structure to be sized for easy and efficient handling and installation. Accordingly, it is desirable for the sprinkler structure to be minimized in weight in relation to, for example, the dry sprinkler weight.